Features an oil metering design that provides uniform metering throughout the entire rpm rangeRollers and axles are manufactured from high-carbon/chromium bearing-quality steel, which is through-hardened for improved wear and load-carrying capability, and the pushrod seat is carbo-nitridedEach unit is 100% tested for proper functionHY-REV™ hydraulic roller lifter features internal hydraulic check valve, which allows for higher rpmMade in the U.S.A.PRO-MAGNUM™ hydraulic roller lifter requires adjustable pushrods.